The effect of olfactory stimulation on energy expenditure in growing preterm infants

Aim: To test the hypothesis that olfactory stimulation in growing healthy preterm infants leads to an increase in resting energy expenditure (REE).

Design: A prospective, randomized clinical trial with crossover was conducted in 20 healthy, appropriate weights for gestational age, gavage-fed preterm infants. Infants were studied while asleep and cared for in a skin servo-controlled convective incubator. Using a pipette, 15 drops of saturated solution of vanillin (Aldrich, Fallavier, France) were dripped to a cloth diaper that was placed on the opposite side of the incubator. REE was measured by indirect calorimetry (DeltaTrac II, Helsinki, Finland) exactly 1 h after feeding. Each infant was studied twice by randomization: after a period of 20 min of vanillin odour or after 20 min without vanillin odour.

Results: We found no statistically significant difference in REE of preterm infants when exposed to vanillin odour (74.5 ± 10.1 kcal/kg/day) in comparison with their REE when not exposed to vanillin odour (79.0 ± 11.3 kcal/kg/day).

Conclusions: Vanillin odour does not significantly influence REE in metabolically and thermally stable preterm infants.